Wheeler added, “The U.S. has made major reductions in NOx emissions, but it’s been nearly 20 years since EPA updated these standards. Through rulemaking and a comprehensive review of existing requirements, we will capitalize on these gains and incentivize new technologies to ensure our heavy-duty trucks are clean and remain a competitive method of transportation.”

From 2007 to 2017, U.S. NOx emissions dropped by more than 40 percent, but there is more work to be done. It is estimated that heavy-duty trucks will be responsible for one-third of NOx emissions from the transportation sector in 2025.

EPA expects that any update to the standards will result in significant mobile source NOx reductions, which will aid communities across the country in the attainment of ozone and particulate matter standards.